This invention relates generally to vacuum cleaning systems and more particularly concerns dual storage dust collectors used with many such systems.
Presently, an upper hopper and lower dump tank or disposable bag are separated by a flapper or gate pivoting on an offset axis with a weight below one side of the axis. The hopper and tank or bag taken together form a single sealed container with the flapper between the tanks. While the hopper and the tank or bag are connected, they are at equalized pressure and the weight tends to hold the flapper closed so that collected dust settles on the closed flapper. When the collected dust overcomes the weight, the flapper drops to deposit settled dust into the dump tank or bag. When sufficient dust has fallen to allow the weight to regain domination of the balance of the system, the flapper closes until the dust again overcomes the weight. Thus, the flapper is continuously bobbing during the operation of the vacuum.
The flapper assembly does not pneumatically seal the hopper from the tank or bag. Consequently, as long as the hopper and the tank or bag remain properly sealed at their connection point, the pressure in the hopper and the tank or bag remains equalized and dust settled on the flapper falls by gravity into the tank or bag. In tank-type collectors, the tank must be removed in order to empty the tank. In bag-type collectors, the disposable bag must be removed from the assembly and tied to seal the bag and a new disposable bag mounted on the assembly. But if the tank or bag were removed while the vacuum was operating, the vacuum would at least momentarily and probably continuously draw additional ambient air through the opening where the tank or bag had been connected to the hopper and through the unsealed portions of the flapper assembly. This would stir up and circulate dust from the tank or bag into the air, returning some of the dust to the cleaned environment. It would also reduce the vacuum power of the unit because of the increase in total area through which ambient air is admitted to the system. Therefore, these vacuum systems are always shut down before the dump tank or bag is removed and remain out of service until the dump tank or a new bag is reconnected. In dust intensive applications, such as in floor grinding and wall sanding operations, the dump tank or bag must be frequently emptied, perhaps multiple times per hour, especially in trades in which workers have contractually established maximum weight-carry limitations. The down time for workers and vacuum equipment while tanks are emptied or bags are replaced can be a considerable proportion of a work day.
It is, therefore, an object of this invention to provide a vacuum cleaner dust collector that can be emptied or replaced while the vacuum is operating. Another object of this invention is to provide a vacuum cleaner dust collector that controls the use of its dust disposal operation independently of the operation of the vacuum cleaner. A further object of this invention is to provide a vacuum cleaner dust collector that is less likely to re-circulate collected dust to the atmosphere during emptying than known dust collectors. It is also an object of this invention to provide a vacuum cleaner dust collector that can be divided into pneumatically separate compartments.